Atheist author and evolutionary biologist Richard Dawkins has warned against celebrating the demise of Christianity, calling it a "relatively benign" faith compared to others, amid reports the religion is "dying" in Europe.

"Before we rejoice at the death throes of the relatively benign Christian religion, let's not forget Hilaire Belloc's menacing rhyme: 'Always keep a-hold of nurse For fear of finding something worse,'" The God Delusion author tweeted to his 2.74 million followers earlier this week.

Dawkins linked to an article from The Guardian, which pointed to a recent report, Europe's Young Adults and Religion, by Stephen Bullivant, a professor of theology and the sociology of religion at St. Mary's University in London, to highlight Europe's "march towards a post-Christian society."

The survey of 16- to 29-year-olds found that a majority of young adults in 12 European countries have no faith. The Czech Republic is the least religious country in Europe, with 91 percent of that age group saying they have no religious affiliation. Between 70 and 80 percent of young adults in Estonia, Sweden and the Netherlands also categorize themselves as nonreligious.

In the U.K., 70 percent of young people identify with no religion, and 59 percent of young people in the country never attend religious services. Additionally, nearly two-thirds of young people in the U.K. never pray.

The most religious country is Poland, where 17 percent of young adults define themselves as nonreligious, followed by Lithuania with 25 percent.

Based on the figures, Bullivant said religion — and Christianity in particular — is inevitably "moribund" in Europe.

"With some notable exceptions, young adults increasingly are not identifying with or practicing religion," he said. "Christianity as a default, as a norm, is gone, and probably gone for good – or at least for the next 100 years."

Bullivant added that many young Europeans "will have been baptized and then never darken the door of a church again. Cultural religious identities just aren't being passed on from parents to children. It just washes straight off them."

The figures for the U.K. in particular, he said, can be explained in part by high immigration.

"One in five Catholics in the U.K. were not born in the U.K.," he said. "And we know the Muslim birthrate is higher than the general population, and they have much higher [religious] retention rates."

Still, he acknowledged that while mainstream churches will become "smaller" over the coming decades, the few people left will be "highly committed" to their Christian faith.

The report corroborates an earlier study from the Pew Research Center, which found that while Christians remain the world's largest religious group, they are declining in Europe, as Christians are "dying faster than they are being born." In contrast, Muslims and the unaffiliated in Europe both experienced natural increases in their populations, with over 2 million and 1 million more births than deaths, respectively, between 2010 and 2015.

Previously, Dawkins, who was famously canned from a Berkeley campus appearance last year after organizers learned about his criticisms of Islam, admitted he has some concern about the decline of Christianity, "in so far as Christianity might be a bulwark against something worse."

"There are no Christians, as far as I know, blowing up buildings. I am not aware of any Christian suicide bombers. I am not aware of any major Christian denomination that believes the penalty for apostasy is death," Dawkins said.

Speaking on another topic during his appearance at the Cheltenham Science Festival, Dawkins warned that Islam as a religion poses a threat more than others.

"It's tempting to say all religions are bad, and I do say all religions are bad, but it's a worse temptation to say all religions are equally bad because they're not," the atheist author said.

"If you look at the actual impact that different religions have on the world it's quite apparent that at present the most evil religion in the world has to be Islam," he stated, contending that moderate Muslims suffer more at the hands of Islam and its teachings than anyone else.